1. Field of the Invention
The present invention relates to security systems for merchandise on display such as articles of clothing, and more particularly to electrical security systems in which alteration of a wire loop extending through a portion of an article secured thereby activates an alarm.
2. History of the Prior Art
A variety of different types of security systems have been proposed for securing merchandise on display such as articles of clothing. In a typical retail store, for example, it is desirable to secure popular and expensive items against the possibility of shoplifting.
Security systems for merchandise include mechanical systems as well as electrical systems. Mechanical systems typically secure the merchandise using a length of cable, chain or the like. In the case of a coat, for example, a length of chain or cable is passed through the sleeve and then secured such as by use of a lock or similar device to form an endless loop. The coat cannot be removed by a potential thief without cutting or otherwise breaking the cable or chain. Many security systems of the electrical type couple a wire or other electrical conductor to the merchandise. If the wire is cut or otherwise broken, an alarm is activated to signal the unauthorized removal of the article.
Examples of mechanical security systems are provided by U.S. Pat. Nos. 3,690,130; 4,336,885; 4,300,690; and 4,204,601. The first two patents described arrangements in which chains attached to the merchandise are passed through slots in the sides of a closable box and then positioned over pegs within the box. The box itself is secured, and the chains cannot be removed from the box without unlocking and opening the box. The latter two of the four patents noted described arrangements in which cables or other restraining devices are secured within slots in the side of a box. A key is required to open the box to permit removal of the restraining devices therefrom.
Mechanical security systems which utilize chains, cables and the like are less than ideal for many applications. Besides being a nuisance to install upon initial display of the merchandise and to remove upon sale of the merchandise or in some cases simply to permit trying on of the merchandise, such devices are easily broken, cut or otherwise defeated by the sophisticated thief. For these reasons electronic security systems present a more attractive alternative for many applications. Typically, electronic security systems employ a wire loop or other sensing device which provides an electrical signal when the loop is cut, broken or otherwise tampered with. The electrical signal in turn is applied to activate an alarm. Such systems tend to be compact, lightweight and easy to install, and quite versatile. The configuration of the wire loops or other sensing devices can be readily varied to adapt to different merchandise displays and different types of merchandise. The alarm may involve sound, a visual signal, a silent signal in a remote location or other possibilities.
Examples of electronic security systems are provided by U.S. Pat. Nos. 883,335; 4,609,919; 2,913,713; 3,253,270; 3,444,547; 3,972,039; and 4,234,879. U.S. Pat. No. 883,335 describes an arrangement in which a plurality of wire loops are coupled in series. The breaking of a loop actuates solenoids and switches to activate an alarm. The circuit has a bypass provision enabling the removal of the sensor loops without triggering the alarm. U.S. Pat. No. 4,069,919 describes an arrangement of serially coupled loops in which apparatus is provided for maintaining circuit continuity so as to prevent activation of an alarm when a loop is absent as well as when both of the enlarged heads of a loop are present in the apparatus. In the arrangement described in U.S. Pat. No. 2,913,712 a single loop is provided with multiple connectors for varying the length thereof so as to accommodate a variety of objects to be secured. In the arrangement described in U.S. Pat. No. 3,253,270 in which plural loops are coupled in parallel, the circuit thereof is initially balanced using a potentiometer. Thereafter, cutting or shorting of a loop unbalances the circuit so as to activate an alarm. Each loop has a plug and jack connection. U.S. Pat. No. 3,444,547 describes an arrangement in which each loop is comprised of a coaxial cable, the inner conductor of which provides a disconnect signal via a latching relay and the outer conductor of which provides a short circuit signal. U.S. Pat. No. 3,972,039 describes a three-wire system which allows loops to be added without activating the alarm. The alarm is activated in the event of removal of a loop plug, the cutting of a loop, or a short circuit. In the arrangement described in U.S. Pat. No. 4,234,879, a loop is connected by plugging into the side of a box.
While present electrical security systems such as those described in the patents referred to are advantageous over mechanical security systems in various respects, such systems leave room for improvement in a number of other respects. For one thing, most such systems are highly complex and specialized in nature in that they respond to only one or a limited number of conditions such as the breaking or other disconnection of a wire loop. It would be better, in this respect, to provide a system of relatively simple design and which would be responsive to any change of state in the circuitry thereof including the connection of a loop thereto as well as the disconnection of a loop coupled thereto. Most electrical security systems are limited in terms of their size and the arrangement thereof to accommodate a variety of different merchandise displays. In this connection it would be advantageous to provide a modular system which involves but a handful of basic components which are readily interconnected with removable connectors and which are easily added to or removed from the system so as to adapt the system to any one of a variety of different applications. Still further advantages would be realized from a security system in which the modular components thereof are mounted such as by special brackets for ease of installation of the system in typical merchandise display arrangements such as T-stands and wall mount arrangements.